Germain Katanga, Jerome Kakwavu, Floribert Kisembo Bahemuka and Bosco Taganda led rival ethnic militias, accused of carrying out massacres, torture and rape in the Ituri district, where some 60,000 people have been killed since 1999.

"The government needs to take these warlords to court, not give them responsible positions in the army," said Alison Des Forges, senior adviser to Human Rights Watch.

'Price of peace'

Information Minister Henri Mova told the BBC's Focus on Africa programme that if the International Criminal Court wanted to prosecute the men, they would be handed over.

"Now we need peace in our country and we decided to appoint them because we can't condemn them before judgement," he said.

"We have a special agreement with the international court to do the job [of investigating war crimes] in place of the government of DRC. Our courts are not very well now - we're a post conflict country."

The BBC's Mark Doyle, who recently visited mineral-rich Ituri, says there are at least seven militia groups there, which are formed along ethnic lines and present themselves as self-defence groups for their communities.

But he says their real purpose is to extract economic rent on behalf of the warlords who control them.

"The big dream of all warlords is to be a general, educated or not, and this is a big problem," said presidential spokesman Kudura Kasongo.

These are the latest appointments under a series of deals intended to bring peace to DR Congo.

Former rebels have also been brought into a power-sharing government.

The process of integrating other former rebel fighters into the army has not been smooth and last year led to fighting around the eastern town of Bukavu as old rivalries flared up again.